DEF Storage Tank Regulation

Feb 21, 2020

DEF STORAGE TANK REGULATION

Source: PEI Journal | Written by Rick Long

REGULATION OF TANKS CONTAINING DEF

BACKGROUND

Nitrogen oxide (NOx) is a major air pollutant that contributes to smog, asthma and respiratory and heart diseases. It’s a by product of diesel fuel’s high combustion temperatures, which results from the high frictional heat levels created by compressing air in the cylinders to the point at which it can ignite diesel fuel without a spark. This is unlike a gasoline engine, which uses spark ignition to burn gasoline.

Beginning in January 2010, no new on-road vehicles can be sold without meeting EPA’s tougher Tier 2 Emission Standards

for Light Duty and Heavy Duty Vehicles. The new standard is 0.2 grams of nitrogen oxide (NOx) per brake horsepower. This regulation will reduce allowable nitrogen oxide levels by 90 percent from today and by 96 percent from 1994.

While gasoline engines have no problem meeting the new standard, vehicles with diesel engines have to utilize new technology to achieve the more stringent emission regulations.

The technology most vehicle and engine manufacturers will rely on is Selective Catalytic Reduction (SCR), which uses a urea-based diesel exhaust fluid (DEF) and a catalytic converter to change smog-forming nitrogen oxides into harmless nitrogen and water vapor. SCR treats exhaust gas downstream of the engine. Small quantities of DEF are injected into the exhaust upstream of a catalyst, where it vaporizes and decomposes to form ammonia and carbon dioxide. The ammonia (NH3) and SCR catalyst then convert the NOx into nitrogen and water.

COMPOSITION OF DEF

Current DEF formulations are a nontoxic, colorless and nearly odorless mixture of 32.5 percent chemical urea and 67.5 percent deionized water. Urea is the nitrogen-containing compound that transforms into ammonia when heated. Similar urea/water compounds are used in various industries, including extensive application as an agricultural fertilizer.

DEF is not a fuel; it also is neither flammable nor combustible. The product is also extremely heavy—at just over nine pounds per gallon.

containers (IBCs), as well as in bulk from both aboveground and belowground tanks.

While the initial supply of DEF will most likely be in packaged containers, larger-scale bulk storage and dispensing is just around the corner. One example suggests why: New truck models will have onboard DEF tanks capable of storing up to 20 (or more) gallons of DEF. A driver with even a mid-sized 13-gallon DEF tank would have to cart and pour almost 120 pounds of packaged DEF for a complete fill-up (13 gallons x 9.2 pounds per gallon = 119.6 pounds).

Given such realities, our industry must understand as quickly and authoritatively as possible how the federal government and

the states plan to regulate larger-scale bulk storage and dispensing of DEF. Good information will be crucial if businesses are to make sound decisions and commitments in the design of their DEF refueling operations.

ABOVEGROUND DRUMS, TOTES, IBCS, AND TANKS

Most people associated with the petroleum marketing and equipment industries know that aboveground tanks (ASTs) storing “oil” are regulated by EPA under the Spill Prevention, Control and Countermeasure (SPCC) rule. Since DEF is composed of aqueous urea which does not meet the SPCC definition of “oil,” ASTs containing DEF (including drums, totes, IBCs and tanks) are not regulated by EPA.

However, a word of caution is necessary here: Some states develop and enforce regulations that are more stringent than the federal rules. Check your state’s aboveground storage tank regulations before installing any AST containing DEF.

Today, the federal EPA estimates that approximately 617,000 underground storage tanks at close to 233,000 facilities operate under the federal UST program. Nearly all these USTs contain petroleum. Most estimates are that less than 10,000 tanks hold hazardous substances covered by the UST regulations.

Just as DEF does not qualify as an “oil” under EPA’s AST program, aqueous urea is not a “petroleum” substance under EPA’s UST program and therefore is not regulated as a petroleum product.

By itself, aqueous urea also falls outside of EPA’s definition of a “hazardous substance.”

Some confusion in the regulatory community develops, however, because DEF may contain up to 0.2% ammonia, and ammonia is one of about 1,200 substances identied as a hazardous substance under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). That becomes important because UST systems that store substances identied as hazardous under CERCLA are subject to the same requirements as petroleum UST systems, except that hazardous substance tanks must have secondary containment and interstitial monitoring. That means hazardous substance USTs must meet the same requirements as petroleum USTs concerning correct installation, spill, overll and corrosion protection, corrective action, and closure.

DE MINIMIS CONCENTRATION?

But another wrinkle may come into play in determining whether CERCLA will apply to UST systems containing DEF.

The federal rules exempt from federal UST regulations “any tank system that contains a de minimis concentration of regulated substances.” Rather than dening de minimis, the rules permit EPA to determine de minimis levels on a case-by-case basis. In the past, EPA has used the de minimis exception to exempt materials with very small, trace amounts of hazardous substances.

Since the amount of ammonia present in DEF USTs is very small, it is very possible that EPA will determine the level of ammonia would be regarded as de minimis and therefore exempt from federal UST regulations.

The industry has two other things going for it which may lead EPA to exempt DEF. First, the DEF manufacturers and others are very concerned not only with incompatible equipment materials causing the DEF to degrade and/or be contaminated, but also with DEF causing corrosion or somehow reducing the integrity of the equipment that can cause risk to the environment.

That, coupled with the willingness of various groups within the DEF community to insist on secondarily contained underground tank systems with interstitial monitors, might help the decision makers at EPA determine that the environmental risk from DEF USTs will be minimized, even absent EPA regulations.

WHAT HAPPENS NEXT?

The ball is now in EPA’s court. EPA is in the process of developing an official interpretation on whether DEF USTs will qualify for the de minimis exemption. We anticipate an answer soon—most likely this summer—but we don’t have one yet. Once EPA issues its interpretation, PEI will let you know.

Please note: As with ASTs, state UST regulations may be more stringent than EPA’s. Check your state’s UST regulations before installing an UST containing DEF. State UST program contact information is available at EPA’s website www.epa.gov/oust/states/statcon1.htm.